Stress Triaxiality and Lode Angle Parameter Characterization of Flat Metal Specimen with Inclined Notch

The stress state has an important effect on the deformation and failure of metals. While the stress states of the axisymmetric notched bars specimens are studied in the literature, the studies on the flat metal specimen with inclined notch are very limited and the stress state is not clearly characterized in them. In this paper, digital image correlation and finite element simulations are used to study the distribution of strain and stress state, that is stress triaxiality and Lode angle parameter. Flat specimen with inclined notch was tested to extract the full field strain evolution and calculate stress state parameters at three locations: specimen centre, notch root and failure starting point. It is found that compared with the centre point and the notch root, the failure initiation point can better characterize the influence of the notch angle on the strain evolution. Conversely, the centre point can more clearly characterize the effect of the notch angle on stress state, since the stress states at the failure point and the notch root change greatly during the plastic deformation. Then the calculated stress state parameters of the flat metal specimen with inclined notch at the centre point are used in Wierzbicki stress state diagram to establish a relationship between failure mode and stress state.

AN INVESTIGATION BY THE BEP-TR METHOD OF THE EFFECT OF OBSTRUCTION ANGLE PARAMETER ON LIGHTING ENERGY PERFORMANCE AND DAYLIGHT SUPPLY

ABSTRACT Following the EN 15193, 2008 Energy Performance in Buildings Regulation in the European Union Member States, a comprehensive calculation can be made on lighting energy performance and daylight effect. This improved model accounts for Turkey’s “BEP-TR” (“Regulation on Energy Performance in Buildings”). In the present study, the effect of the obstruction angle parameter of buildings on lighting energy consumption and daylight provided is examined through a sample hotel project by the BEP-TR calculation method. This study investigates the effect of daylight on lighting energy performance alternatives that were produced according to the height, building distance variations (causing obstruction angle), and the correlation between annual lighting consumption values, daylight supply factor, and obstruction parameters. Accordingly, the current study aims to develop a method to assist zoning regulations, building intervals, and height decisions by determining specific ratios between obstruction parameters, daylight supply factor and lighting energy consumption values. Results of this study clearly show that obstruction parameter variables affect both the daylight supply factor and annual lighting energy significantly.

3D X-ray based Method for Diagnostics of Spinal Deformities

Research Funding: The “OrthoLine” research and production company has provided funding for the research study. Conflict of interest: The authors have no conflicts of interest to declare. Research Objective: to revise the “arc angle” parameter for estimating the value of spinal curvature and, if necessary, to search for another parameter or to develop another method for mathematically correct estimation of spinal deformity value. Materials and methods. The critical analysis has been performed both theoretically and experimentally. It has been demonstrated that the angle parameter is incorrect, and another estimation parameter and procedure should be developed. A method of 3D X-ray diagnostics and construction of 3D structure using two orthogonal projections of two-dimensional spine image involve several procedures. Software-based scaling and horizontal-wise image synchronization, synchronised selection of spinal arc on images and construction of a geometric image of the studied arc are performed stepwise. Software-based measurements of a number of geometric parameters on 2D images, utilised for mathematical analysis and construction of a 3D picture of geometric spine images, are made, and geometric parameters of some arcs, among which the arc plane curvature and azimuth angle are assumed to be the major ones, are found. 2D X-ray diagnostics was performed using a light-dose device AGFA DX – D 300, which allows having the images of the entire spinal column in a single shot. Results. A method for the 3D X-ray diagnostics of the pathologically deformed spine has been proposed. The relationship between the deformity value and severity and the true arc curvature and azimuth angle of the arc plane position between frontal and lateral planes of the trunk has been established. There have been developed the procedures for software-based examination of 2D orthogonal images of the trunk projections and computation of parameters of the 3D spine state along with constructing its true image. There has been created a two-parameter function, with correction factors, of spinal deformity degree based on comparative estimations of radiographic images, measured parameters, and posture of the pathologically deformed trunk, made by independent experts. Conclusion. The developed method of 3D X-ray diagnostics and analysis of radiographs eliminates critical errors of conventional method. What principally distinguishes this method is a research object, namely, a three-dimensional state of the spine rather than two-dimensional on the frontal projection, and the use of the arc curvature parameter and azimuth angle of the arc plane position instead of mathematically erroneous angle parameter – the Cobb angle. The method of (3D) X-ray diagnostics provides new beneficial properties of the 2D spondylography based on state-of the-art digital technologies.

Modelling the structural variation of quartz and germanium dioxide with temperature by means of transformed crystallographic data

The pseudocubic (PC) parameterization of O4 tetrahedra [Reifenberg & Thomas (2018). Acta Cryst. B74, 165–181] is applied to quartz (SiO2) and its structural analogue germanium dioxide (GeO2). In α-quartz and GeO2, the pseudocubes are defined by three length parameters, a PC, b PC and c PC, together with an angle parameter αPC. In β-quartz, αPC has a fixed value of 90°. For quartz, the temperature evolution of parameters for the pseudocubes and the silicon ion network is established by reference to the structural refinements of Antao [Acta Cryst. (2016), B72, 249–262]. In α-quartz, the curve-fitting employed to express the non-linear temperature dependence of pseudocubic length and Si parameters exploits the model of a first-order Landau phase transition utilized by Grimm & Dorner [J. Phys. Chem. Solids (1975), 36, 407–413]. Since values of tetrahedral tilt angles about 〈100〉 axes also result from the pseudocubic transformation, a curve for the observed non-monotonic variation of αPC with temperature can also be fitted. Reverse transformation of curve-derived values of [Si+PC] parameters to crystallographic parameters a, c, x Si, x O, y O and z O at interpolated or extrapolated temperatures is demonstrated for α-quartz. A reverse transformation to crystallographic parameters a, c, x O is likewise carried out for β-quartz. This capability corresponds to a method of structure prediction. Support for the applicability of the approach to GeO2 is provided by analysing the structural refinements of Haines et al. [J. Solid State Chem. (2002), 166, 434–441]. An analysis of trends in tetrahedral distortion and tilt angle in α-quartz and GeO2 supports the view that GeO2 is a good model for quartz at high pressure.

Vibratory Conveying by Harmonic Longitudinal and Polyharmonic Normal Vibrations of Inclined Conveying Track

Vibratory conveying of a material point by harmonic longitudinal and polyharmonic normal vibrations of an inclined conveying surface is considered. The dependence of dimensionless conveying velocity – a ratio of velocity to the product of frequency and amplitude of longitudinal vibration – on several dimensionless parameters is investigated in the moving modes without hopping. Maximal conveying velocity is achieved at the certain values of normal vibration amplitudes and phase difference angle between the longitudinal and normal vibrations, which are called optimal. Their values are dependent on two dimensionless parameters: the inclination angle parameter – a ratio of an inclination angle tangent to a frictional coefficient, the intensive vibration coefficient – a ratio of the longitudinal amplitude of vibration to the amplitude of the first harmonic of normal vibration and frictional coefficient. In a condition of the intensive longitudinal vibration, when its amplitude significantly greater than amplitudes of normal vibration, dimensionless velocity is almost independent of the intensive vibration parameter and it depends only on inclination angle parameter, i.e. on inclination angle and frictional coefficient. The optimal values of harmonics' amplitudes of polyharmonic normal vibration are determined in dependence of inclination angle parameter with the number of harmonics from 2 to 7. The graphs of considered dependencies are presented and the most important values of parameters are presented in the table. Conclusions are made to determine the optimal vibration parameters and the problems of further research are indicated. The considered vibrations can be used in different vibratory conveying devices with electromagnetic drives.

Lorentz invariance violation and modified Hawking fermions tunneling radiation of stationary axially symmetric black holes

Based on a higher energy scale, the dispersion relation might be corrected. Correspondingly, the Hamilton–Jacobi equation should also be modified. In this paper, we use the correction to study the fermion tunneling radiation for a Gibbons–Maeda–Garfinkle-Horowitz–Strominger (GMGHS) black hole, a Kerr–NUT black hole, and an Einstein–Maxwell–Dilaton–Axion (EMDA) black hole. The result shows that compared to the charged GMGHS black hole and the rotating Kerr–NUT black hole, the Hawking temperate and the entropy of the rotating charged EMDA black hole not only are related to the correction parameter [Formula: see text] and particle mass [Formula: see text] but also depend on the angle parameter [Formula: see text] of the black hole coordinates.

A non-destructive method for monitoring the ripening of tomatoes based on their induction of chlorophyll fluorescence

Maturity is one of the most important factors associated with assessing the quality of tomatoes. The aim of this study is to develop a new device to measure the degree of ripeness of tomato fruits based on chlorophyll fluorescence. The results of this method, chlorophyll fluorescence, were compared with those of the widely used colorimeter for this purpose. Botanical variety of tomatoes “Alkazar” was used with different stages of maturity: green, breakers, turning, pink, light red, and red. The results indicated that specific parameters of the slow induction of chlorophyll fluorescence, such as the maximum chlorophyll fluorescence (Fm) and the coefficient of specific photosynthetic activity (Rfd), can be used to classify tomato fruits according to their maturity stage, as efficiently as the hue angle parameter of the color measurements. A correlation coefficient between the hue angle and the slow induction of chlorophyll fluorescence parameters was 0.96 with Fm, and 0.97 with Rfd. Using the hue angle or Fm, the fruits of all six-maturity stages were accurately classified. In conclusion, the developed device method is a non-destructive, innovative, convenient, and less time-consuming than the color-based method.

Optimization of vibratory conveying upward by inclined track with polyharmonic normal vibrations

The paper is devoted to the research of vibratory conveying of piece goods along an inclined track, performing harmonic longitudinal and polyharmonic normal vibrations. It is considered the conditions of reaching maximum conveying velocity at specified values of frequency and amplitude of longitudinal vibrations – the conditions of maximum dimensionless conveying velocity, depending on several dimensionless parameters in the moving modes without hopping. These dimensionless parameters are the inclination angle parameter – a ratio of an inclination angle tangent to a frictional coefficient, the intensive vibration coefficient – a ratio of the longitudinal amplitude of vibration to the amplitude of the first harmonic of normal vibration and frictional coefficient. Maximal conveying velocity is achieved at the certain values of normal vibration amplitudes and values of phase difference angles between longitudinal and normal vibrations, which are called optimal, and their values are dependent on these two dimensionless parameters, while maximum normal vibration acceleration should be equal to the gravitational acceleration. The research was made by approximate harmonic balance method and by numerical step-by-step integration method, which allows performing calculations with any given accuracy. The results obtained by the two methods are compared. To determine the maximal and optimal values of elevation angles, there are calculated the maximal value of the inclination angle parameter at which the value of dimensionless velocity is equal to zero, and the value of the inclination angle parameter at which a particle moves to a specified height in the minimum time. The optimal values of amplitudes of harmonics of polyharmonic normal vibration are determined in dependence on the inclination angle parameter with the number of harmonics from four to seven. The graphs of these dependencies are presented and the most important values of dimensionless parameters are presented in the table.

Correlation Investigation for Uniform Circular Array Based on Measured Massive MIMO

In this paper, the performance of a two-dimensional (2D) Massive MIMO angle parameter system with a uniform circular array (UCA) topology at base station is studied based on the field measurements in indoor line-of-sight (LOS) scenario at a frequency of 4.45[Formula: see text]GHz. Many spatial parameters are extracted, including angle information and correlation characteristic. It is shown that correlation lies between antenna elements and users. It is illustrated in the envelope correlation coefficient which goes on a downward trend while the antenna spacing is increasing in the measurements.